In general, spatial light modulators (SLM), such as digital micromirror devices (DMD), deformable micromirrors, liquid crystal on silicon (LCOS), ferroelectric liquid-crystal-on-silicon, reflective, transmissive, and transflective liquid crystal displays (LCD), and so forth, contain a large number of individual light modulators. SLMs have been used for creating images for use in image display systems. In addition to displaying images, these SLMs may also be used in other applications wherein there is a need to optically process light.
An example of such an application is optical networking. In optical networking, SLMs may be used for optical switching, optical signal attenuation, and so on. Light modulators in an SLM may be used to reflect or pass light to various positions to perform optical switching, while in optical signal attenuation, some light modulators in the SLM may be configured to not reflect or pass light to attenuate the optical signal. For example, if the SLM is a DMD, then micromirrors in the DMD may be pivoted to a desired position in order to switch an incoming light beam, while to attenuate an optical signal, a number of the micromirrors in the DMD may be pivoted away from an intended target to cause a loss in optical signal power, wherein the loss in optical signal power may be dependent on a pattern of the micromirrors and the number of micromirrors in the pattern pivoted away from the intended target.
In optical networking applications, it may be necessary to keep the light modulators of an SLM in a specified state for an extended period of time, sometimes on the order of months or years. Therefore, it may be possible to cause degradation, such as permanent burn-in, of the light modulators by having them maintain a single state for the extended amount of time. Furthermore, the power density of the light used in optical networking applications may be higher than that of light used in image display applications. The greater power density may lead to greater operating temperatures, which may help to further accelerate the performance degradation of the light modulators. Degradation of light modulators may not be a significant problem in image display applications since the light modulators tend to rapidly change states while displaying images and not remain in a single state for an extended period of time. In some SLM technologies, such as the DMD, the performance degradation can be reduced or eliminated by operating the pixels for a period of time in an opposite state or by cycling through states.